If the ABS light goes off shortly after you start the car then you're OK; it's just the system running a check. If you manually turn "off" TRACS, which means the light on the dash will be on, it will remain so until you turn off the ignition. When you start the car again TRACS automatically turns "on" which means the dash indicator will not be visible. In other words you can't turn off TRACS and leave it off permanently. At least that's how it works on my V70 XC AWD. Hope this helps.

Dear Adam.

Your question about how the tracs works is pretty simple.

When the driving wheels start to slip the ABS computer recives a signal

that one wheel is spinning faster than the opposite wheel,so the abs computer will act in a opposit way,it will feel the slip and apply some brake pressure to the slipping wheel trying to slow it down.

But be awere tracs only works good in speeds up to 25mph after that it is your own responsibility to keep track of what you are doing

Adam- welcome to the world of unexplained volvo problems!!! Myself and many other Bricksters on the 850 board are experiencing the same problem. Remember, your car is the same as 96-2000MY 850/S/V70s(which is the same as my 850 T5). Anyway, your ABS control unit is probably bad. Will HAVE to replace it. You will need to let dealer pull the codes and it will probably say "faulty wheel sensors" or the like. Since you got the warranty, I hope it covers that part. My car is out of warranty, so I have to cough up the approx. $600(parts & labor). Alot of us think Volvo should offer a recall on this unit(it fails for no reason), but so far I'm still wishing.

Hope this helps, Billy D in NY.